U.S. patent number 7,029,150 [Application Number 10/763,785] was granted by the patent office on 2006-04-18 for catadioptric light distribution system.
This patent grant is currently assigned to Guide Corporation. Invention is credited to Timothy S. Finch.
United States Patent |
7,029,150 |
Finch |
April 18, 2006 |
Catadioptric light distribution system
Abstract
A Catadioptric Light Distribution System that collects and
collimates the hemispherical pattern of light emitted by a
Lambertian light emitting diode (LED) into a collimated beam
directed essentially parallel to the optical axis of the LED. The
system comprises a circular condensing lens having a center axis
that is aligned with the optical axis of the LED parabolic
reflector having circular opening formed therethrough which is
centered on the center axis of the parabolic reflector and a double
bounce mirror. The light reflected and culminated by the parabolic
reflector is directed onto the circular annular double bounce
mirror so that this light is collimated in an annular beam which
passes around the edge of the condensing lens.
Inventors: |
Finch; Timothy S. (Fishers,
IN) |
Assignee: |
Guide Corporation (Pendleton,
IN)
|
Family
ID: |
34795133 |
Appl.
No.: |
10/763,785 |
Filed: |
January 23, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20050162854 A1 |
Jul 28, 2005 |
|
Current U.S.
Class: |
362/298; 362/301;
362/300; 362/299 |
Current CPC
Class: |
F21S
43/30 (20180101); F21S 43/14 (20180101); F21V
13/12 (20130101); F21V 7/0025 (20130101); F21Y
2115/10 (20160801) |
Current International
Class: |
F21V
7/00 (20060101) |
Field of
Search: |
;362/298-302,305,328-329,335,346-347,349,520 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Shea; Sandra
Assistant Examiner: May; Robert
Attorney, Agent or Firm: Ice Miller LLP
Claims
I claim:
1. A catadioptric light distribution system comprising: a light
emitting diode (LED) having an optical axis and capable of emitting
light in an essentially hemispherical pattern distributed 360
degrees around said optical axis and in multiple directions from
zero degrees along the optical axis to approximate 90 degrees
measured from the optical axis; a circular condensing lens having a
center axis aligned with said optical axis and positioned apart
from said LED, said condensing lens configured to receive and
collimate a central cone of the light emitted from said LED, said
cone of light being essentially centered around said optical axis;
a parabolic reflector having a center axis aligned with said
optical axis of said LED, said parabolic reflector having a
circular opening formed therethrough centered on said center axis,
said opening dimensioned to allow said cone of light from said LED
to pass through said parabolic reflector and impinge on said
condensing lens, said parabolic reflector positioned around said
LED to receive tat portion of the light emitted by said LED that
does not pass through said opening; said parabolic reflector
configured to direct said light received from said LED in an
annular beam in a direction parallel to the optical axis but in a
direction away from said condensing lens; a circular annular double
bounce minor configured and positioned to receive the annular beam
of light from said parabolic reflector and reverse the direction of
that light 180 degrees and form in an annular collimated beam
essentially parallel to said optical axis around said condensing
lens; whereby substantially all of the light emitted by said LED is
collimated into a beam of light substantially parallel to said
optical axis of said LED.
2. A catadioptric light distribution system as claimed in claim 1
wherein said LED is a Lambertian pattern LED.
3. A catadioptric light distribution system as claimed in claim 1
wherein said condensing lens is positioned and has a diameter
sufficient to receive a cone of light from said LED having a
conical angle of between about 30 and about 50 degrees measured
from the optical axis.
4. A catadioptric light distribution system as claimed in claim 1
where in said parabolic reflector is dimensioned and configured to
receive a toroid of light from said LED having a toroidal angle of
the difference between about 30 to about 90 degrees to the
difference between about 50 to about 90 degrees measured from said
optical axis.
5. A catadioptric light distribution system as claimed in claim 1
where in said circular annular double bounce mirror comprises a
first circular annular mirror having, in cross section, a flat face
angled at essentially 45 degrees as measured from said optical
axis, said first circular annular mirror having a first interior
circular edge and a first exterior circular edge, and a second
circular annular mirror having a second circular interior edge
joined to said first exterior circular edge of said first circular
annular mirror, and a second circular exterior edge, said second
circular annular mirror having, in cross section, a flat face that
is at an angle of essentially 90 degrees with respect to said first
circular annular mirror.
6. A catadioptric light distribution system as claimed in claim 5
wherein said circular condensing lens has a diameter and said first
circular exterior edge and said second circular interior edge have
a diameter that is substantially equal to said diameter of said
condensing lens.
7. A catadioptric light distribution system for an automobile
comprising: a Lambertian pattern light emitting diode (LED) having
an optical axis and capable of emitting light in an essentially
hemispherical pattern around said optical axis; a circular
condensing lens having a focal point and a center axis aligned with
said optical axis and positioned with said LED at said focal point
of said condensing lens, said condensing lens configured to receive
and collimate a central cone of the light emitted from said LED,
said cone of light being essentially centered around said optical
axis; a parabolic reflector having a focal paint and a center axis
aligned with said optical axis of said LED, said parabolic
reflector having a circular opening formed therethrough centered on
said optical axis, said opening dimensioned to allow said cone of
light from said LED to pass through said parabolic reflector and
impinge on said condensing lens, said parabolic reflector
configured and positioned around said LED to receive that portion
of the light emitted by said LED that does not pass through said
opening; said parabolic reflector configured to direct said light
received from said LED in an annular beam in a direction parallel
to the optical axis but in a direction away form said condensing
lens; a circular annular double bounce mirror configured and
positioned to receive the annular beam of light from said parabolic
reflector and reverse the direction of that beam of light 180
degrees and form in an annular collimated beam around said
condensing lens essentially parallel to said optical axis; whereby
substantially all of the light emitted by said LED is collimated
into a beam of light substantially parallel to said optical axis of
said LED.
8. A catadioptric light distribution system as claimed in claim 7
wherein said condensing lens is positioned and has a diameter
sufficient to receive a cone of light from said LED having a
conical angle of between about 30 and 50 degrees as measured from
the optical axis.
9. A catadioptric light distribution system as claimed in claim 7
where in said parabolic reflector is dimensioned and configured to
receive a toroid of light from said LED having a toroidal angle of
the difference between about 30 to about 90 degrees to the
difference between about 50 to about 90 degrees as measured from
said optical axis.
10. A catadioptric light distribution system as claimed in claim 7
where in said circular annular double bounce mirror comprises a
first circular annular mirror having, in cross section, a flat face
angled at essentially 45 degrees as measured from said optical
axis, said first circular annular mirror having a first interior
circular edge and a first exterior circular edge, and a second
circular annular mirror having a second circular interior edge
joined to said first exterior circular edge of said first circular
annular mirror, and a second circular exterior edge, said second
circular annular minor having, in cross section, a flat face that
is at an angle of essentially 90 degrees with respect to said first
circular annular mirror.
11. A catadioptric light distribution system as claimed in claim 10
wherein said circular condensing lens has a diameter and said first
circular exterior edge and said second circular interior edge have
a diameter that is substantially equal to said diameter of said
condensing lens.
12. A catadioptric light distribution system as claimed in claim 11
wherein said parabolic reflector has an exterior diameter that is
substantially the same as the diameter of said condensing lens.
Description
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a catadioptric light distribution
system for collimating a hemispherical pattern of light distributed
by a lambertian light emitting diode into a collimated beam of
light directed essentially along the optical axis of the LED. More
particularly, the present system relates to a catadioptric light
distribution system that can be used to culminate a beam light from
an LED for automotive lighting purposes.
2. Detailed Description of the Prior Art
Light emitting diodes, commonly called LEDs, are well known in the
art. LEDs are light producing devices that illuminate solely as a
result of electrons moving in a semi-conductor material.
Consequently, LEDs are advantageous as compared to filament type
bulbs because an LED has no filament to burn out. Consequently,
LEDs generally have a life as long as a standard transistor, and as
a result have been utilized in a variety of different devices where
longevity of the light source is important. Originally, LEDs were
quite small and limited in their capacity to produce light.
However, advances in the technology have increased the amount of
light (luminous flux (Lm) or radiometric power (mW)) that an LED is
capable of producing. Consequently, practical applications for LEDs
have been expanded to include automotive lighting purposes.
Lambertian LEDs are also well known in the art. LEDs typically have
a hemispherical top that is centered on an optical axis through the
center of the LED, however other top surfaces can be used. The
light emitted by the Lambertian LED is in a hemispherical pattern
from 0.degree. to approximately 90.degree. measured from the
optical axis and 360.degree. around the optical axis. In addition,
LEDs are typically mounted on a heat sink that absorbs the heat
generated by the LED when it is producing light.
Unfortunately, conventional optical systems cannot culminate all of
the light emitted by a Lambertian LED because of the wide spread of
light emitted by and physical constraints of a Lambertian LED. For
example, U.S. Pat. No. 6,558,032-Kondo et al. illustrates one prior
art attempt to effectively distribute light from a Lambertian LED.
However, the various light distribution systems illustrated in
Kondo et al. are not very effective in collimating the light from
an LED into an effective beam.
Accordingly, it is a primary object to the present invention to
provide a catadioptric light distribution system that effectively
collimates substantially all the light emitted by a Lambertian LED
into a beam of light essentially parallel to the optical axis of
the LED.
SUMMARY OF THE INVENTION
A catadioptric light distribution system in accordance with the
present invention comprises an LED having a central optical axis
and which is capable of emitting light in a hemispherical pattern
distributed 360.degree. around the optical axis and from 0.degree.
to approximately 90.degree. measured from the optical axis. A
circular condensing lens having a center axis is aligned so that
the center axis of the circular condensing lens coincides with the
optical axis of the LED. The condensing lens is positioned apart
from the LED and the condensing lens is configured to receive and
collimate a central cone of light emitted from the LED that is
centered around the optical axis. A parabolic reflector is also
provided. The parabolic reflector has a center axis through the
center of the parabolic reflector which is aligned with the optical
axis of the LED. The parabolic reflector also has a circular
opening through the parabolic reflector that is centered on the
optical axis. The circular opening is dimensioned to allow the cone
of light from the LED to pass through the parabolic reflector and
impinge upon the condensing lens. The parabolic reflector is
positioned around the LED in a position to receive that remaining
portion of the light emitted by the LED that does not pass through
the opening. The parabolic reflector is configured to redirect the
light received from the LED into an annular beam that is focused in
a direction parallel to the optical axis but in a direction away
from the condensing lens. A circular annular double bounce mirror
is positioned and configured to receive the annular beam of light
from the parabolic reflector and reverse the direction of that
light a 180.degree. so that it forms an annular culminated beam
around the outside edge of the condensing lens. The light
culminated by the condensing lens and the light culminated by the
circular annular double bounce mirror form a single culminated beam
parallel to the optical axis.
Thus, the present invention collects substantially all of the light
emitted by a Lambertian LED and focuses that light into a
culminated beam in a direction along the optical axis of the
Lambertian LED.
DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a prior art system using a Lambertian LED and a
parabolic reflector.
FIG. 2 illustrates a prior art system using a Lambertian LED and a
condensing lens.
FIG. 3 is a top view of a preferred embodiment of the present
invention.
FIG. 4 is a cross sectional side view of the preferred embodiment
of the present invention taken along lines 5--5 in FIG. 3 showing
the light distribution produced by the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 discloses a prior art system which uses a Lambertian LED 10
and a parabolic reflector 12. Because of the heat generated by a
LED, the LED includes a heat sink 14 on the back of the LED. The
parabolic reflector 12 is configured to culminate light generated
at the focal point of the paraboloid and culminate that light
outwardly. The LED is placed at the focal point of the parabolic
reflector and it is facing the parabolic reflector 12 and aligned
so that the optical axis of the LED and the center axis of the
parabola 16 are aligned. Because the Lambertian LED emits light
360.degree. around the optical axis and from 0 to about 90.degree.
as measured from the optical axis, a hemispherical light
distribution pattern is produced. Unfortunately, because of the
heat sink 14 mounted on the base of the Lambertian LED 10, light
reflected by the center of the parabolic reflector 12 is
essentially blocked by the heat sink 14 so that a dark shadow
column as depicted by the dotted lines 18, is produced in the
center of reflector system. Thus, a significant portion of the
light emitted by the Lambertian LED 10 is blocked by the heat sink
14 in this prior art system.
FIG. 2 represents another prior art system for culminating the
light produced by a Lambertian LED 10. A circular condensing lens
20 is positioned apart from the LED 10 with the center axis of the
condensing lens 20 aligned with the optical axis 16 of the
Lambertian LED. Thus, the condensing lens 20 receives a cone of
light from the LED 10 with the conical angle of the cone of light
being a function of the diameter of the condensing lens 20. Because
a condensing lens is capable of effectively culminating light
impinging upon its surface an angle no greater than approximately
50.degree., that portion of the hemisphere of light produced by the
LED as shown by arrows 22 in FIG. 2 cannot be effectively
collimated. This reduces the amount of light from the LED that can
be focused into a collimated beam using this prior art system.
With reference to FIGS. 3 and 4 a preferred embodiment of the
present invention is illustrated. An LED 10 is shown mounted on a
heat sink 14. The LED 10 has an optical axis 16 which extends
upwardly as shown in FIG. 3. A circular condensing lens 30 is
positioned apart from the LED with the center axis of the circular
condensing lens aligned with the optical axis 16 of the LED and the
LED at the focal point of the condensing lens 30. The condensing
lens 30 typically has a first flat face 32 and a second curved face
34. A parabolic reflector 36 is positioned so that its center axis
aligns with the optical axis 16 of the LED 10 and its focal point
aligns with the LED. The parabolic reflector 36 has a circular
opening 38 formed there through which opening is centered on the
center axis of the parabolic reflector 36.
Positioned behind the LED 10 and also centered on the optical axis
of the LED is a circular annular double bounce mirror 40. With
reference to FIG. 4, it can be seen that the circular annular
double bounce mirror 40 comprises a first circular annular mirror
42 which in cross section has a flat reflecting surface 44 which is
angled at an angle "a" that is 45.degree. as measured from the
optical axis 16. The circular annular double bounce mirror 40 also
comprises a second circular annular mirror 46 which in cross
section has a flat mirror surface 48 that is aligned at an angle of
90.degree. with respect to the flat mirror surface 44. The circular
annular mirror 42 has a first interior circular edge 50 with a
first exterior edge 82. First interior circular edge 50 defines a
circular opening 52 aligned around the optical axis 16. The
circular annular mirror 42 also has a second exterior circular edge
58 and a second interior edge 84 joined to the first exterior edge
82. Second exterior circular edge 58 extends entirely around the
perimeter of the circular annular double bounce mirror 40. Mirror
42 has two reflecting surfaces 44 and 48 oriented 90.degree. with
respect to one another and which are joined along an edge 56.
With reference to FIG. 4, parabolic reflector 36 has an interior
edge 60 which defines the condensing lens aperture 38 centered on
the optical axis 16 and an exterior edge 62 which defines the
circular open face of the parabolic reflector 36. Parabolic
reflector 36 has an interior curved reflecting surface 64 which is
formed to receive a toroid of light from the LED 10 and reflect
that light in a culminated annular beam towards the flat mirror
surface 44 of first circular annular mirror 42.
The aperture 38 in parabolic reflector 36 allows a cone of light
having a conical angle of "b" to pass through the aperture 38 and
impinge upon the flat surface 32 of condensing lens 30. The
combination of the flat surface 32 and the curve surface 34 of lens
30 are configured to culminate the cone of light passing through
aperture 38 into a beam of light parallel to the optical axis 16 as
shown by the arrows 70 in FIG. 4. The conical angle "b" may
typically be between 30 and 50 degrees as measured from the optical
axis. Angle "b" is a function of the diameter of condensing lens 20
and the diameter of opening 38 in parabolic reflector 36. These
diameters can be varied to allow as broad a cone of light that can
be effectively collimated by lens 20 to be passed through aperture
38.
Similarly, a toroid of light from LED 10 strikes the curve surface
64 of parabolic reflector 36. That toroid of light can have a
toroidial angle "c" the difference of between about 30.degree. to
about 90.degree. (i.e. 60.degree.) as measured from the optical
axis to between the difference about 50.degree. to 90.degree. (i.e.
40.degree.) as measured from the optical axis depending on the
conical angle "b" of the cone of light passing through opening 38.
That toroid of light is reflected downwardly in a collimated
annular beam of light onto flat mirror surface 44 which, in turn,
directs the light 90 degrees across to the flat surface 48 of
second annular circular mirror 46 which, in turns, reflects the
light 90 degrees in a direction parallel to the optical axis 16 as
illustrated by the arrows 72 in FIG. 4. Thus, the circular annular
double bounce mirror redirects the light by 180.degree..
Because the circular edge of condensing lens 30 essentially
coincides with the circular junction 56 of surfaces 44 and 48 of
annular mirror 42 because the diameters are substantially the same,
the light reflected by the circular annular double bounce mirror
forms an annular beam which passes by the edge of circular
condensing lens 30 and blends with the light collimated by
condensing lens 20. As can be seen by FIG. 4, substantially all of
the hemispherical pattern of light distributed by the Lambertian
LED 10 is effectively culminated into a beam of light parallel to
the optical axis 16 as is depicted by the arrows 70 and 72.
While elements of the preferred embodiment illustrated in FIGS. 3 4
are shown floating without visible support, it should be understood
by one of ordinary skill in the art that appropriate structural
supports such as a lens holder may be supplied to support the
various elements of the system. It should also be expressly
understood that various modifications, alterations or changes may
be made to the preferred embodiment illustrated above without
departing from the spirit and scope of the present invention as
defined in the appended claims.
* * * * *